Origin of Apes and Hominids

Origin of Apes and Hominids - H erectus evolved into H...

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Origin of Apes and Hominids Two hypotheses differ on how and where Homo sapiens originated. 1. The Out-of-Africa Hypothesis proposes that some H. erectus remained in Africa and continued to evolve into H. sapiens , and left Africa about 100,000- 200,000 years ago. From a single source, H. sapiens replaced all populations of H. erectus . Human populations today are thus all descended from a single speciation event in Africa and should display a high degree of genetic similarity. Support for this hypothesis comes from DNA studies of mitochondria: since African populations display the greatest diversity of mitochondrial DNA, modern humans have been in Africa longer than they have been elsewhere. Calculations suggest all modern humans are descended from a population of African H. sapiens numbering as few as 10,000. 2. The Regional Continuity Hypothesis suggests that regional populations of
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Unformatted text preview: H. erectus evolved into H. sapiens through interbreeding between the various populations. Evidence from the fossil record and genetic studies supports this idea. Which hypothesis is correct? Scientists can often use the same "evidence" to support contrasting hypotheses depending on which evidence (fossils or molecular clock/DNA studies) one gives more weight to. The accuracy of the molecular clock, so key to the out-of-Africa hypothesis, has recently been questioned. Recent studies on the Y-chromosome seem to weaken the regional continuity hypothesis by indicating a single point-of-origin for our species some 270,000 years ago. Continued study will no doubt reveal new evidence and undoubtedly new hypotheses will arise. It is a task for all of us to weigh the evidence critically and reach a supportable conclusion, whether we are scientists or not....
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